Hydraulic mechanical control for air breathing starter



Oct. 1964 J. H. FERGUSON, JR., ETAL 3,151,451

HYDRAULIC MECHANICAL CONTROL FOR AIR BREATHING STARTER Filed Oct. 11, 1962 39 37 AIR 29 GENEAATGA lOl 67 IOl I09 I25 :fi 8| FIG.

FIG. 2

INVENTORS JOHN H. FERGUSON JR. DENNEN J. BUNGER (N. ATTORNEY United States Patent 3,151,451 HYDRAULIC MECHANICAL CONTROL FOR AIR BREATHING STARTER John H. Ferguson, Jr., Utica, and Dennen J. Bunger,

Whiteshoro, N.Y., assignors to The Bendix Corporation, Utica, N.Y., a corporation of Delaware Filed Oct. 11, 1962, Ser. No. 229,888 5 Claims. (Cl. fill-39.14)

This invention relates to means for starting jet engines and more particularly concerns starting systems and controls therefor in which air is compressed and burned with fuel to provide hot gases for driving a turbine starter unit.

An object of the present invention is to provide an improved air breathing starter system in which hydraulic means and controls reliably and safely initiate and control a turbocompressor, gas generator which provides gases to a turbine starter unit.

A further object is the provision of such a starter system in which fuel pressure and/or electricity are initially derived from the hydraulic means whereby the system is wholly independent of the vehicle having the engine to be started.

Another object is the provision of such a starter system in which hydraulic controls cooperate with devices to sense pressure, speed and temperature to give proper starter operation in respect to initiation, engine starting, and cut-off.

An additional object is to provide such a starter system which does not require an external electrical supply, conserves the electricity which it generates, and is conditioned automatically for another start.

The realization of the above objects, along with the features and advantages of the present invention, will be apparent from the following description and the accompanying drawing in which:

FIGURE 1 is schematic showing of the starting system of the present invention having a gas turbine starter unit and hydraulic controls and initiating means with the controls in position for initiating the starter unit.

FIGURE 2 is schematic showing of the controls of FIGURE 1 when positioned for cranking-up an associated jet engine.

Referring to the upper part of FIGURE 1 of the drawing, it can be seen that a schematic representation of a starting system having a turbocompressor, hot gas generator and a free-turbine, starter unit has'been shown. An air inlet 11 is provided for directing air to the radiallyoutward-flow compressor 13 which discharges into the curved, annular inlet channel 15 of the combustor or annular combustion chamber 17. The compressed air in the combustion chamber is mixed with fuel from spray nozzles 19 and 21 and ignited by spark plug 23. The combustion products are discharged from the combustion chamber 17 to the curved outlet duct 25. These hot combustion products pass through the compressor or gasproducing turbine 27 which is an integral part of the compressor 13. Compressor 13 and turbine 27 can be referred to as a turbocompressor unit. This unit has a hollow shaft 29 extending axially to the left. The gas is discharged from the compressor turbine 27 to a radiallyinwardly-flowing free turbine 31. The free, powerproducing turbine 31 has a solid shaft 33 extending to the left and encased by the coaxial turbocompressor shaft 29 which terminates short of the end of shaft 33. Hollow shaft 29 provides support for the starter turbine shaft 33 by means of a conventional bearing therebetween, such as an air bearing. Shaft 29 has mounted thereon at the right a spur gear 35 which meshes with a start-up, spur gear 37. Gear 37 is connected through an overload disc clutch 39 to a hydraulic initiator or pump-motor 41.

Patented Got. 6, 1964 The left end part 43 of drive shaft 33 has connected at its end a power transmission train including a speedreducing means 47 and an overrunning clutch 49. The overruning clutch 49 has connected thereto an externallysplined shaft or connector 51 for connection to a jet engine (not shown).

A first, centrifugally-operated, speed sensing device 53 is operatively associated with drive shaft 33. A second, centrifugally-operated, speed-sensing device 55 is operatively associated with tubular shaft 29. Speed sensors 53 and 55 are mechanically linked by tube 57 and rod 58 respectively to device 60 whereby at predetermined speeds the spring-biased piston 59 of a control device 60 will be urged downwardly to open hydraulic valve 60. At the right, a main fuel control valve 61 connects through a thermal cut-out valve 62 to initiating check valve 63 and starting check valve 64. The anti-dribble check valve 64 is located at the main fuel supply line 67 while fuel check valve 65 is located in start up fuel supply line 69. A duct 71 extends from the annular combustion chamber 17 at the bottom and connects to a pistontype control device 73, a branch duct 75 has a sensing tube 76 extending to thermal switch 62 and connects to another piston-type control device 77 which opens a switch 79. The piston control 77 is mechanically linked to a two-way rotary selection valve 81.

The fuel line 67 receives fuel from fuel pump 83 which is fed by pipe 85 from the vehicle fuel supply tanks (not shown). Pump 83 which has pressure regulation through a by-pass and check-valve (not shown) is driven by gear 87 connected thereto which in turn meshes with a spur gear 89 mounted on drive shaft 29. Gear 89 also meshes with another spur gear 91 which is connected to a lubrication pump 93 for providing lubrication to the starting system by means not shown. To the left from lubrication pump 93, an abort switch 95 is provided in a circuit 96 having a solenoid coil 97. This coil 97 is arranged so that rod 57 and spring-biased piston 59 of control device 60 is moved downwardly when abort switch 95 is closed and thus permits pressurized hydraulic fluid to flow through pipe 98 to the bottom of spring-biased piston 99 in fuel control valve 61. This action causes piston 99 to move upwardly to block fuel line 67 and thus stop the starting system.

The pressurized hydraulic fluid is delivered from pump 41 via discharge pipe 101 to the automatic, two-way selection valve 81 which, when positioned as shown, passes fluid via pipe 103 to control device 60, shown as blocking flow to pipe 98 and hence the flow to the bottom of piston 99 of normally-open fuel valve 61. Fluid also passes from selection valve 81 via pipe 105 to reservoir 107 which has outlet pipe 109. Outlet pipe 109 has a check valve 111 and connects to the pump feed pipe 113 so that a circuit is provided from pump 41 to reservoir 107 and back to pump 41. A branch pipe 115 connects into reservoir outlet pipe 109, has therein a manually-operable pump 117, and connects to accumulator 119. This accumulator 119 has a gas or air chamber 121 with a valved inlet pipe 122 below a flexible diaphragm 123 so that energy can be stored for pressurizing the fluid by an external source, by manual pump 117 or (as will appear) by the discharge from motor-pump 41 when driven by starter turbine 13. Suificient hydraulic energy is stored either initially or by recharging during the starting cycle to accelerate the gas generator to self-sustaining speed. Pressure gauge 124 will indicate the correct pressure.

The accumulator outlet pipe 125 has a manual, start valve 127 therein and connects to pump feed pipe 113.

It is apparent that, when the spring-biased, normally tubular shaft 29 and compressor 13. Shaft 29 (thus powered by the fluid from accumulator 119) will also turn generator 129 since connected to spur gear 131 which meshes with spur gear 35 on shaft 29 adjacent compressor 13. Generator 129 supplies electricity via circuit 133 having switch 79 and signal light 134- to ignition coil 135 and spark plug 23 so that ignition is elfected as pressurized air and fuel (from pump 83) are supplied to combustion chamber 17. Generator 129 also supplies via wire 96 the electricity for the abort control solenoid 97 when abort switch 95 is closed.

Referring to FIGURE 2 of the drawing which shows the principal control elements of FIGURE 1, it can be seen that the start valve 127 has been closed, the selection valve 81 has been rotated, the piston 59 of control device 60 has moved down, and the piston 99 of fuel control valve 61 has moved up. With these positions, it is apparent that the starting system is in its cut-off stage or condition.

In operation, the accumulator 119 is suitably pressurized either from a previous starting operation or manually by pump 117. Gauge 124 will show the proper pressure. A suitable gas supply can be used for pressurizing since valved inlet 122 to accumulator 119 has been provided. The pilot opens normally-closed, start valve 127 which causes operation of hydraulic motor-pump 41. Pump 41 then drives compressor 13, fuel pump 83, generator 129, and lube pump 93. Selection valve 81 (positioned as shown in FIGURE 1) permits how of energizing fluid to reservoir 107 (with check valve 111 in reservoir outlet pipe 199 closed) and permits flow to the blocking side of piston 59 of control device 60. Fuel pressure is generated by fuel pump 83 as a function of the speed of compressor 13 and fuel is delivered through the normally-open, thermal-responsive, shut-off valve 62 which will sense a predetermined, unsafe temperature in the combustion chamber 17. During this primary, starterwind-up period, sulficient fuel pressure exists to open the initiating, anti-dribble, check valve 63 supplying the initiating nozzle 21 only and electricity is delivered through the normally-closed, pressure-responsive switch 79 to the signal light 134, the abort switch 95, the coil 135 and spark plug 23. As initiating nozzle 23 sprays fuel into the low-pressurized air provided by accumulator fluid driving the compressor 13, ignition occurs and combustion gases result. The accumulator 119 is sized to provide motoring for the time required for the gas generator to reach self-sustaining speed after ignition, which speed will be related to a predetermined combustion pressure, when a secondary period of operation begins.

At this speed-pressure point, the pilot notes that signal light 134 has turned off by the opening of switch 79 and releases the start valve 127 so that it closes and the compressor-turbine-driven, motor-pump 41 restores accumulator pressure for a subsequent start. If the pilot does not close the start valve 127 at the beginning of the sec ondary period, the cycle will not re-initiate because pressure cannot be built up in the accumulator 119 with start valve 127 open. At the start of the secondary period, combustion pressure opens, as mentioned, switch 79 and the ignition circuit is interrupted to shut down the spark plug 23 and further turns automatic selection valve 81 via device 77 and its linkage so that motor-pump 41 repressurizes the accumulator 119 by drawing fluid from the reservoir 107. Device 77 could be also linked to close start valve 127.

During the secondary period, sufiicient fuel pressure is developed to open the starting fuel spray valve 64 and a larger amount of fuel is sprayed from the starting nozzles 19 so that maximum power will develop.

At a predetermined starter cut-off speed at shaft 33 and as shown in FIGURE 2, the speed device 53 actuates control device 6% so that pressurized fluid passes to the fuel control valve 61 causing it to close off the fuel supply.

Hydraulic pressure maintains the down positioning of the speed-responsive, control device so that fuel valve 61 remains closed. Combustion stops and, as the turbine 27 slows down, the fuel pressure decays, said fuel valves 19 and 21 close. Without combustion pressure, selection valve 81 repositions as shown in FIGURE 1 and, as hydraulic pressure bleeds oil? to the reservoir 107, the fuel valve 61 opens and the piston 59 of the speed control 60 returns to starting or up position. It is to be noted that the starting cycle can be aborted by closing switch 95. Additional speed safety is provided since, compressorturbine 27 can not run away to dangerous speed because its speed sensor 53 will also actuate control 60 and hence close main fuel valve 61. After reaching jet-engine starting speed, the associated jet engine will disconnect via sprag clutch 49 and over-run the starter.

It is to be understood that changes can be made in the disclosed embodiment of the inveniton by persons skilled in the art without departing from the invention as set forth in the following claims.

What is claimed is:

1. An air breathing starting system for high speed turbine engines comprised of:

a hot gas generator including an air inlet, a compressor arranged to receive air from said inlet, a first turbine coupled to the compressor, a combustor arranged to receive compressed air from said compressor, fuel supply means and igniting means arranged to admit fuel and to provide ignition temperature in said combustor,

a starter unit having a second turbine free of mechanical connection to said first turbine or said compressor, a power transmission train connected to said second turbine having speed reducing means, an overrunning clutch and a connector for the turbine engine to be started,

gas flow means arranged to direct hot gases from said combustor through said turbines whereby the transmission train and the compressor can be powered, and

hydraulic means including a pressurized accumulator,

a pump-motor, and a reservoir,

said pump-motor being connected to said first turbine,

said fuel supply means including a fuel pump connected to said first turbine,

said igniting means including an electrical generator connected to said first turbine,

said hydraulic means being arranged so that said first turbine and hence said fuel pump and said electrical generator are operated to provide self-sustaining combustion in said gas generator,

said fuel supply means being arranged to be interrupted when said second turbine rotates at a predetermined speed for starting of a turbine engine by said starter unit, and

said hydraulic means being further arranged so that said accumulator is re-pressurized by said pumpmotor after self-sustaining combustion exists in said combustor and while said second turbine is rotating up to said predetermined speed.

2. An air breathing starting system according to claim 1 and being further characterized by:

said hydraulic means having a select valve responsive to the pressure of self-sustaining combustion in said combustor so that the select valve automatically directs the output of said pump-motor to said accumulator for re-pressurizing during starting operation by said starter unit. 3. An air breathing starting system according to claim 1 and being further characterized by:

said igniting means having a pressure-responsive switch connected to said combustor and arranged to disconnect said electrical generator at a pressure corresponding to self-sustaining combustion in said combustor.

4. An air breathing starting system according to claim 1 and being further characterized by:

said fuel supply means having a normally-open control valve operable to closed position by said hydraulic means when said fuel supply means responds to said predetermined speed of said second turbine. 5. An air breathing starting system according to claim 4 and being further characterized by:

a start valve in said hydraulic means between said accumulator and said pump-motor, flow means connecting said accumulator to said hydraulic means between said start valve and said pump-motor, a two-way select valve in said hydraulic means between said pump-motor and said reservoir, conduit means connecting said two-Way select Valve to said accumulator, and

a piston device connected to saidcombustor and responsive to self-sustaining combustion pressure to operate said valve to direct the output of said pumpmotor to said accumulator for re-pressurizing when said start valve is closed.

References Cited in the file of this patent UNITED STATES PATENTS Nardone Aug. 29, 1939 Nardone Oct. 7, 1941 Stalker Aug. 25, 1953 Schmider et al. Dec. 9, 1958 Van Nest et a1 Nov. 17, 1959 Stevens Feb. 23, 1960 FOREIGN PATENTS Great Britain Oct. 11, 1961 

1. AN AIR BREATHING STARTING SYSTEM FOR HIGH SPEED TURBINE ENGINES COMPRISED OF: A HOT GAS GENERATOR INCLUDING AN AIR INLET, A COMPRESSOR ARRANGED TO RECEIVE AIR FROM SAID INLET, A FIRST TURBINE COUPLED TO THE COMPRESSOR, A COMBUSTOR ARRANGED TO RECEIVE COMPRESSED AIR FROM SAID COMPRESSOR, FUEL SUPPLY MEANS AND IGNITING MEANS ARRANGED TO ADMIT FUEL AND TO PROVIDE IGNITION TEMPERATURE IN SAID COMBUSTOR, A STARTER UNIT HAVING A SECOND TURBINE FREE OF MECHANICAL CONNECTION TO SAID FIRST TURBINE OR SAID COMPRESSOR, A POWER TRANSMISSION TRAIN CONNECTED TO SAID SECOND TURBINE HAVING SPEED REDUCING MEANS, AN OVERRUNNING CLUTCH AND A CONNECTOR FOR THE TURBINE ENGINE TO BE STARTED, GAS FLOW MEANS ARRANGED TO DIRECT HOT GASES FROM SAID COMBUSTOR THROUGH SAID TURBINES WHEREBY THE TRANSMISSION TRAIN AND THE COMPRESSOR CAN BE POWERED, AND HYDRAULIC MEANS INCLUDING A PRESSURIZED ACCUMULATOR, A PUMP-MOTOR, AND A RESERVOIR, SAID PUMP-MOTOR BEING CONNECTED TO SAID FIRST TURBINE, SAID FUEL SUPPLY MEANS INCLUDING A FUEL PUMP CONNECTED TO SAID FIRST TURBINE, SAID IGNITING MEANS INCLUDING AN ELECTRICAL GENERATOR CONNECTED TO SAID FIRST TURBINE, SAID HYDRAULIC MEANS BEING ARRANGED SO THAT SAID FIRST TURBINE AND HENCE SAID FUEL PUMP AND SAID ELECTRICAL GENERATOR ARE OPERATED TO PROVIDE SELF-SUSTAINING COMBUSTION IN SAID GAS GENERATOR, SAID FUEL SUPPLY MEANS BEING ARRANGED TO BE INTERRUPTED WHEN SAID SECOND TURBINE ROTATES AT A PREDETERMINED SPEED FOR STARTING OF A TURBINE ENGINE BY SAID STARTER UNIT, AND SAID HYDRAULIC MEANS BEING FURTHER ARRANGED SO THAT SAID ACCUMULATOR IS RE-PRESSURIZED BY SAID PUMPMOTOR AFTER SELF-SUSTAINING COMBUSTION EXISTS IN SAID COMBUSTOR AND WHILE SAID SECOND TURBINE IS ROTATING UP TO SAID PREDETERMINED SPEED. 